Lumos
by doctorg
Summary: A Harry Potter AU written as a gift for the Sterek Secret Santa gift exchange. The giftee asked for Slytherin!Stiles and Gryffindor!Derek as enemies-to-friends. :-) Stiles Stilinski / Derek Hale.


"Hey."

Derek pulled his attention from the Advanced Potions book with a scowl, glancing up into amber, smiling eyes. It was that Stilinski kid again. He was becoming the bane of Derek's existence — always seeming to show up wherever Derek was, ruining his peace with his loud sunny laugh and his mobile distracting mouth and his stupid pretty eyes…

Derek reined in his errant thoughts, his scowl deepening as he took in the group of Slytherin kids lingering a few steps behind Stiles. "You and your friends can have this bench in a minute," he growled. "I'm almost done."

"Oh, hey — I wasn't — I mean, you don't have to —"

Derek ignored the kid's babbling, shoving the last of his sandwich into his mouth and standing up, gathering up his books. Sure, he had planned on lingering awhile in the open air and sunlight while he studied, but that hardly meant anything to the Slytherin brats, did it?

"All yours," he snarled.

The Stilinski kid was just staring at him, that soft pink mouth open, his face flushed pink. As Derek returned his stare he finally seemed to kick his brain into gear. "Thanks?" he said uncertainly.

Great, not even a real thank you. Derek huffed in irritation and stalked off, past the group of Slytherins who seemed to be avidly watching. Lydia Martin — the red-headed girl who always seemed to be where Stiles was, Allison Argent — who Derek carefully avoided eye contact with, and Danny. Danny was in Derek's Transfiguration class, and he seemed like an okay guy, for a Slytherin.

Or maybe not. "Real smooth, Stilinski," Derek heard Danny mutter as he settled on the bench.

"Stiles, you're _hopeless_ ," Lydia added.

Maybe they thought Stiles should have been more forceful in evicting Derek from the bench. It was just like a Slytherin to think they were entitled to whatever they wanted, when they wanted it. Derek shrugged off the exchange and went to find a new reading spot.

* * *

The Potions room was dark and abandoned at this hour of the night, a single ball of _lumos_ floating overhead to light Derek's workstation. Derek concentrated intently, muttering the list of complex steps to himself. This was the most dangerous part of the process, one wrong move and —

"Oh, hey! It's you!"

The bright voice startled Derek, making him fumble the vial of powdered wolfsbane in his hand. He dropped the vial, caught it in midair, and then watched in horror as the resulting jolt sent a puff of pale purple dust into the air.

"Hey, Derek! What are you doing here so late? I thought everyone was gone —" Stiles was babbling on, apparently oblivious to the calamity he had caused, as Derek carefully stoppered the vial with a cork and pulled off the leather gloves he had been wearing. He wasn't sure exactly what was going to happen, but it wasn't going to be good.

A few scant moments later he felt his throat close up, his heart pounding wildly as his body tried to expel the wolfsbane powder from his constricted lungs. He stumbled backwards, feeling his legs give way underneath him, sending him crashing to the floor. He scuttled defensively back until the cool stone of the wall was pressed against his spine, his whole body trembling. He pressed his forehead to his knees, curling into himself, his chest heaving with the attempt to bring in air through his spasming windpipe.

"Derek!" Stiles' voice was muffled by the roar of Derek's own heartbeat in his ears, but his hand against Derek's cheek was warm and grounding. "Derek, look at me."

Stiles' voice was crisp and authoritative, so different from his usual laughing tone that Derek couldn't help but obey, his eyes meeting Stiles' in surprise. "Good. That's good," Stiles said, the warmth of his voice seeming to creep in, unknotting some of the pressure in Derek's chest. "Now breathe with me, in through your nose, and out through your mouth. In...two...three...out...two...three. In...two...three...out...two...three. That's it."

Stiles was so close Derek could see every variegation in his amber eyes, could feel the warm puff of his breath as he spoke. He held Derek's hand pressed tight to his chest, letting him feel the rise and fall of the smooth muscles as he breathed in and out. Derek focused on that feeling, of Stiles' hand covering his own, of the warm, solid strength of Stiles beneath his robes. He wasn't matching his pace to Stiles' instructions at all but he was managing to slow the sharp, rapid gasps into jagged, shuddering breaths.

"Just like that — I know you can do this, Derek. In...two...three...out...two...three." Stiles' other hand pressed gently on Derek's shoulder, forcing him to uncurl a little from his reflexive hunch, the action clearing his lungs a little more. "You're doing great, I'm right here with you. In...two...three...out...two...three."

Derek didn't know how long they sat there — Stiles counting and Derek sweating and shaking, trying to match the pace of Stiles' calm, clear voice with huffs of unsteady breath. Finally he could feel the effects of the wolfsbane ease, his throat opening up a bit, the violent spasm of his lungs diminishing. His heart still beat frantically in his chest but the erratic pulse of it was easing, steadying in time with the thump of Stiles' own heart.

"You okay now?" Stiles eventually asked. He accepted Derek's unsteady nod, turning to sit in a heap next to him, his back also pressed to the wall. "Christ, but you scared the life out of me!" Stiles said, and if Derek had had the breath to laugh at the irony of it, he would have. He noticed that Stiles still held Derek's hand in his, and seemed in no hurry to relinquish it. The ball of _lumos_ overhead slowly dimmed as Derek's spell faded away, leaving only the rays of the three-quarters moon to light the cavernous room.

"I used to have them too," Stiles eventually said. Derek didn't feel up to talking yet, but whatever noise he made seemed to communicate his confusion. "Panic attacks," Stiles clarified. "I used to get them all the time, after my mom died. Felt like I was dying, it was awful. In any case, my dad used to talk me through them, just like that. He's — he's a Muggle, but he's great. I mean, I like it here, and I really want to learn, but —" Stiles' voice turned as shaky as Derek felt right now. "I _miss_ him sometimes. You know what I mean?"

All Derek could do was squeeze Stiles' hand in sympathy. He knew, all too well, what it was like to miss his family. They sat there in silence for longer than Derek would have thought Stiles could manage. Now that the effect of the wolfsbane had cleared his system, Derek felt exhausted and empty, strangely content to just sit side by side with Stiles as his legs fell slowly asleep on the stone cold floor. Stiles' breaths were quick but even, his heartbeat rapid but steady. Several times he seemed to gather his breath to speak but then hesitated as if reluctant to break the silence — fidgeting for a few moments with a rustling of his robes before lapsing back into quietude.

Derek finally turned his head to look at Stiles, his profile limned in silver moonlight. His eyes were downcast, long lashes dark against his mole-dotted cheeks. He was chewing on his lower lip, catching the plumpness of it between his teeth and then releasing it, over and over.

"You can talk," Derek finally said, his voice coming out rough and gravelly.

Stiles' eyes flew wide, his gaze meeting Derek's for a long, intense moment before he dropped it again, laughing weakly. "Well, I know there's _something_ about me you don't like, and I figured — for most people, it's the talking," Stiles muttered, shrugging. "I know I talk too much, and even more when I'm nervous, and —" His words trailed off, and he seemed intently interested in the ribbon trimming the cuff of his robe now, fiddling with it until it threatened to break loose.

"I don't — _dislike_ you," Derek said, feeling wrong-footed, not realizing how weak it sounded until it came out of his own mouth.

Stiles' mouth twisted for a moment, his expression hurt before he shrugged again, pulling his lower lip back between his teeth.

"Why do you _care?"_ Derek couldn't help asking. This didn't make sense at all — wasn't it always people like _Stiles_ who hated _Derek_ , so completely and summarily that Derek hadn't thought of anything except to respond in kind?

"I wanted to be your friend," Stiles said, his voice low and serious, his heartbeat giving no sign of a lie.

"But — you have lots of friends," Derek stammered.

Stiles' eyes lifted to Derek's, wide and sincere. "I wanted to be _your_ friend."

Derek felt suddenly shy and confused, too exposed under that clear gaze. He pushed himself to his feet, shaking imaginary dust from his robes.

Stiles watched him for a moment and then, with a sigh, stood himself. "What were you doing here so late anyway?" Stiles asked, his quick eyes grazing over the vials and flasks laid out on the workbench.

Derek stumbled forward, hurriedly putting his body in front of the book of potions recipes, still open to the one he had been working on. "Don't you have someplace else to be, Stilinski?" He tried to make the words sound haughty but they came out embarrassingly plaintive instead.

Stiles paused from where he had been stepping forward, hand outstretched to touch one of the vials. "Oh," he said quietly, taking a step back. "Yeah. I guess — I guess I do."

Derek felt something twist in his belly at having put that subdued tone into Stiles' bright, happy voice. "I'll — I'll see you tomorrow," he finally said. "We have Herbology together, right?"

"Yeah." Stiles smiled, a little hesitantly. "See you there."

* * *

Stiles was still everywhere that Derek went, but somehow instead of being annoying, it was...companionable. Stiles sat next to Derek in Herbology, distracting him with the way he chewed on the end of his quill. He was quick and sharp, his mind seeming to wander sideways half the time and leap three steps ahead of the instructor at other times. Instead of eating meals at his house table with his Slytherin friends, Stiles more and more often seemed to find Derek, sitting outside with his own meal, settling himself at Derek's side without invitation and chattering on about whatever had happened to him that day. It was...soothing, to have Stiles at his side, expecting nothing in the way of conversation from Derek, content to have him listen.

Stiles even dragged Derek to a Quidditch game, the first he had gone to since he had watched Laura play. The initial sadness faded quickly as Derek became engrossed in the game, even cheering loudly when Gryffindor scored, ignoring the good-natured jeering from Stiles and his Slytherin friends.

That was something else that was surprising to Derek. Since he lost his family he had kept himself at a distance from all his classmates, even those in his own house. He had always considered the Slytherins to be the worst of the lot, but Stiles and his friends were nothing like he had expected them to be.

They were all brilliant at their studies — Lydia was probably on her way to being the most talented practitioner of Arithmancy of their generation, Danny was genius both at the Muggle technology of computers as well as with Alchemy, and Stiles seemed to be able to master whatever he turned his capricious mind to. He spent an entire week learning Mermish, just so he could ask the selkies of Black Lake what kind of games they played. He returned dripping wet and half-frozen, having ultimately exchanged a set of waterproof playing cards for a bag of carved river rocks — the selkie game of skitter that was surprisingly diverting to play. Which was fortunate, because Derek and Stiles spent long hours in front of the fire in the Infirmary, tossing the stones while Stiles sniffed and sneezed miserably with the cold he had caught and then suffered through Madam Pomfrey's even more-repellent cure.

Aside from their quick wits, however, Stiles and his friends did not seem to fit Derek's preconceived notions about Slytherins. Lydia had an icy demeanor at first, but her obvious affection for her friends — especially Stiles, who had been her best friend since first form — was evident in her every action. Danny was easygoing and calm, bringing warmth and balance to the group. And Allison —

Derek had avoided Allison for as long as he could, until finally she had sought him out in private. He expected some kind of warning, but instead she had apologized for the actions of her family members. She had told Derek that she had been wanting to tell him so for ages, but hadn't wanted to hurt him further by bringing up the painful history. Her eyes shone with tears as she denounced the prejudices of her grandfather and aunt. It was impossible to stay aloof from that sincerity, and when Derek had stammered out that he didn't blame her for their actions, her obvious relief and dimpled smile had eased the tension between them.

And so somehow, surprisingly, Derek found himself to have _friends_. And then there was Stiles, who seemed somehow _more_ than a friend. Not that Derek would ever act on the way he felt, but sometimes — when their shoulders were pressed together while they leaned against the same tree at lunch, or when their legs brushed under the library table while studying for their N.E.W.T.s — at times like that Derek sometimes wondered if maybe he wouldn't _have_ to be the one to act. If maybe _Stiles_ would lean over and press those plush lips to his, or rub his ankle up Derek's calf in invitation…

But despite his lingering glances and the subtle sway of his body toward Derek's, Stiles never actually acted, and Derek was left to wonder, and to wait.

* * *

The end of the first term was approaching. The grounds of Hogwarts were frosted with snow, and the students tired and frazzled from revising for exams. Derek hadn't seen Stiles all day, and then finally, as evening fell, he almost ran right into him entering the library as Derek was leaving.

"Derek!" Stiles' eyes had dark smudges underneath them, his hair sticking straight up at odd angles, but his smile was wide and bright.

"I was — I was just going to get something to eat," Derek mumbled.

"Oh! I'll come with you," Stiles said, looking down at the books and papers loaded into his arms.

"No, you — you were on your way —" Derek began, gesturing at the library door.

"No, it's no trouble, I'll just —" Stiles fumbled his books and papers, shoving them forcefully into his overfull messenger bag. It seemed almost inevitable when the frayed leather strap finally snapped, sending the messenger bag crashing to the ground, papers sliding across the floor, quills scattering everywhere.

"Maleficent's broom!," Stiles cursed as he crouched down, gathering up the spilled contents of his bag, but Derek was frozen in place. He could only stare at the piece of paper that had come to rest near his foot — and more specifically, at the three faces smiling and up at him, waving at the camera. "Laura Hale Awarded International Wizarding Order of Merit," the Daily Prophet headline read, the paper yellowed with age, ragged and curled at the edges.

"What." Derek said, his voice coming out thin and wavering.

Stiles' head jerked up before following Derek's gaze. Any hope that Derek might have had that this was just some sort of mistake, some odd coincidence, was dispelled instantly by the look of guilt on Stiles' face. He grabbed at the paper, face flushed pink, and shoved it into his bag, hiding the animated faces of Derek's sister and parents. "Derek, I —"

Derek found his feet already moving, desperate to get out of the stuffy corridor, into the fresh air. Stiles had been pretending to be his friend and instead he had been — what — _investigating_ him?

"Derek, wait!" Stiles had abandoned the rest of his papers and quills and was pelting after Derek. "Just, let me explain!"

Derek quickened his steps. He could feel the pressure building within him, the ache of claws at this fingertips, the itch of fangs at his gums. He reached the door, pulling hard at the ancient brass handle.

"Derek, just _wait!"_ Stiles had grabbed the sleeve of his robe and Derek wheeled around, yanking it free.

"Wait for _what?_ To hear whatever Slytherin lie comes out of your mouth next?" Derek spat. "What was this, some kind of _joke_? Or a _dare?_ Pretend to be my friend, while the whole time —"

"No!" Derek wondered if he would even be able to hear a lie in Stiles' rapid heartbeat. Maybe he had figured out a way around that too. "It's just — people were saying all kinds of things about your family — that they were Death Eaters, that they were killed supporting You-Know-Who, and I _knew_ it couldn't be true, I just wanted to _know_ —"

" _Death Eaters."_ Derek's voice came out rough and broken. Of all the strange rumors, of all the whispers overheard by his sensitive wolf ears, he had never heard that one. The idea of it made his gut feel sick and hollow. Talia and Rodrigo Hale, his parents — his _heroes_ — Death Eaters? _That_ was what people believed?

"Derek —" Stiles' face was pale, his eyes enormous and pleading, and Derek couldn't even look at him. He felt a snarl rise to his lips, saw the reflection of his eyes glowing red in Stiles' irises, and Stiles cringed back in fear.

Derek pushed past him and out the door, running now, through the Porticus Imago, out the exterior door, past the hedge and the courtyard. His thoughts were a tangled jumble — he just had to get clear, just had to get _safe_. As the grounds turned from snowy manicured lawns to tall slushy grass and shrubbery he shed his bag and his scarf, his shoes and his socks, his robe and the rest of his clothing, his whole body twisting and shivering in midair as he leapt into his wolf form, running for the darkness of the Forbidden Forest.

* * *

He ran for what seemed like hours, the wolf form muting the unhappy roil of his human thoughts, instead focusing his senses on the sights and sounds and smells of the Forbidden Forest. It had been too long since he had allowed himself a full shift, and he gloried in the strength of his muscles, the symphony of scents, the rush of the wind as he ran and ran and ran. The other students feared the Forbidden Forest but it held no dangers for him, the creatures that inhabited it as respectful of his beast form as he was of theirs.

Finally he started to tire, slowing his bounds to a slow pad, turning his way toward home, footsore and exhausted. The sounds of the Forbidden Forest surrounded him, the chittering of birds, the whinnying of unicorns, the far-off whomp of the Willow. Derek let himself be soothed by it, his ears pricking and turning, tracking the call of a Centaur herd, the fizz and pop of will 'o wisps. Suddenly, however, a new sound reached him, distant and hoarse.

"Derek!"

Derek trotted cautiously toward the sound.

"Derek!" The call grew louder as Derek approached, finally peeking his head around a bush to look.

Stiles looked exhausted and bedraggled, his robe slushy and muddy to his knees, his face scraped. He held his wand defensively in one hand, a bundle of fabric clutched against his chest in the other, and he smelled of magic and blood and salt.

Derek took a step closer, his instinct to comfort at odds with his newfound wariness. It was practically suicide for a student to be out in the Forbidden Forest alone, after dark, and Stiles looked like he had been out here for _hours_.

He watched as Stiles' head snapped around, knew the moment Stiles saw the glow of his red eyes. Instead of the fear he expected, however, Stiles dropped to his knees in the slush, a harsh sob of relief escaping him.

"Derek!" Stiles wiped his forearm across his eyes, smearing the tears away, making a bigger mess of mud and blood across his fair skin. "Thank Gandalf, I found you."

Derek padded a few cautious steps toward Stiles. Stiles may have found a way to have hidden a lie in his voice or his heartbeat, but there was no way of hiding his scent from Derek's wolf form, and his smell was pure sadness and relief.

Derek edged even closer, waiting for the acrid tinge of fear to color Stiles' own soft, warm scent. Instead, Stiles held his hand out, reaching to lay a gentle palm on Derek's fur.

"I'm so sorry," Stiles mumbled brokenly. "I just — I just _liked_ you, and I wanted to know more about you, and you never tell me anything, and you know how I get when there's something that I don't know, and it was _wrong_ , I know it, but I just wanted — I just wanted to be close to you, in some way, because — because of the way I feel about you. And it's okay if you don't feel the same way, or even want to be my friend anymore, I'll understand —"

Stiles' face was buried in Derek's ruff now, his arm tight around Derek's neck. Derek pulled back a little, swiping his tongue across Stiles' face, tasting the mud and blood and tears, surprising him into silence. Then he shivered, stretched, and tumbled his way back into his human form.

Stiles' mouth was gaping open, his eyes wide as they skimmed over Derek's body and then shyly away. He wordlessly held out the bundle of fabric, and Derek recognized his robe. It was thick with the smell of himself and Stiles, mixed together, and Derek slipped it over his head, comforted by the combined scents.

It took Derek a few moments to find his human voice again. "You knew I was a werewolf," he finally rumbled.

Stiles nodded. "I guessed, when I saw — you were making Wolfsbane Potion. But I wasn't sure until the hall, and your eyes —"

"You don't mind?"

"Mind? No, it's — it's cool. Kinda badass, in fact."

Derek found himself searching Stiles' face, finding only sincerity.

"Not everyone feels that way," he mumbled finally, dropping his gaze to his bare, dirty feet.

"That's what happened to your family, isn't it?" Stiles' voice was hesitant, but he pressed on, his scent tinged with determination. "I mean, it seemed like it was covered up pretty well, but you know me, I'm good at — at research, and I saw where Kate Argent got sent to Azkaban —"

"Yeah." Derek took a deep breath, and then let it out slow. "She tricked me. She was a student here, but much older than me. She pretended — she acted like she liked me, and I told her all about us. About our house. She said she was going to come, and I could introduce her to mom and dad, but instead she — she burned them all. The house was still smoking when Laura and I got there."

" _Merlin's blood,"_ Stiles breathed. "Derek, I'm — I'm so sorry. And I'm sorry I betrayed your trust like that, I should have just — just been patient."

Derek felt a reluctant smile quirk his mouth. "That doesn't sound like you at all."

"Oh yeah?" Stiles smiled in return, bumping his shoulder against Derek's. "Smartass Wolf."

Derek could have let it rest there, could have headed back with Stiles without another word, but something about the night was making him feel brave, and reckless. "You said — you said you had _feelings_ —"

A pink blush spread under the muck on Stiles' face. "If you — I mean, I didn't mean to make things weird between us, if —"

Derek leaned in, kissing the rest of the words off Stiles' lips, feeling his mouth go slack with surprise before Stiles surged forward, practically throwing himself into Derek's lap. The kiss was slow and sweet. Stiles tasted of salt and hot chocolate, and made the most amazing little noise of protest when Derek finally pulled free, gasping for breath.

"Okay, then." Stiles' smile was blindingly bright. "I guess that answers a whole lot of questions."

Derek smiled in return. He pushed himself to his feet, reaching out to grab Stiles' hand and pull him upwards as well. Hand-in-hand, they walked through the forbidden forest, stopping every now and again to trade soft kisses, leaning into each others' warmth.

"Look," Stiles said softly as they approached a small clearing. Derek followed the path of his outstretched finger. A small herd of Thestrals grazed the snowy ground, wings fluttering gently at their sides.

"You see them?" Derek asked in wonder. He had always felt like the only one, everyone else remarking on the self-driving carriages that took the elder students from Hogsmeade station to Hogwarts.

"Yeah." Stiles' voice was tinged with sadness. "I know people think they are scary, but I think — they're kind of beautiful, aren't they?"

Derek looked at the boy next to him — the one who had followed a wolf into the Forbidden Forest — afraid for Derek's safety, uncaring of his own. The boy who seemed to see beauty in everything, including Derek's own guarded and fractured soul.

"Yeah," Derek said, his eyes on Stiles' profile. "Beautiful."

Stiles' smile was soft and warm as he took Derek's hand back in his, the two of them leading each other back towards the warm and welcoming lights of Hogwarts.


End file.
